The long-term goal of this study is the development of preventive or therapeutic measure for benign prostatic hyperplasia (BPH). The specific aims are to evaluate the relations of the hormone profile to surgery for BPH, to evaluate the associations of cigarette smoking with hormone levels, and to evaluate associations of smoking and other environmental factors, especially diet, to BPH and to the hormone profile. A case- control study is proposed. The case series will be 500 men living in Rhode Island who have their first operation for BPH in the period May, 1989 - April, 1992. A series of 1,000 controls will be selected from residents of the study area. Subjects will be interviewed at home with respect to smoking and dietary histories. The dietary history will use the food frequency method supplemented with food models to help estimate portion size. Subjects will also be asked for blood specimens before and after the interview. Serum from each subject will be pooled and analyzed for free and bound testosterone, dehydrotestosterone, free and bound estradiol, estrone, delta4-androstenedione, androstanediol, and prolactin. The relative incidence of surgically-confirmed BPH will be estimated according to quintile of hormone levels, and according to smoking history and intakes of nutrients including total fat, saturated fat, carotenoids and fiber. Based on information from the controls, cigarette smoking and nutrient intakes will be related to hormone levels.